Brain Network Connectivity Dynamics during Voluntary Finger Movement in Right Handed Adults with Down Syndrome: Evidence for Contralateral and Ipsilateral Dominance

摘要

We previously reported that in a small group of right handed adults with Down syndrome (DS), voluntary finger movements were characterized by ipsilateral dominance. The aim of this study was to examine the dynamics of network connectivity during the same motion. Thirteen typical adults and twelve adults with DS participated in this study. Cortical responses were recorded with a 151 channel MEG system (VSM MedTech). Subjects pressed a button on the keypad using their right index finger. The SAM beamformer was used to obtain spatial distributions of the evoked activity in 0.2 - 50Hz, 0.2-12Hz and 12-50Hz frequency bands. Individual distributions were spatially normalized to a standard template brain using SPM and averaged. Locations with the highest evoked signal to noise ratio in the normalized averaged data were found, and transformed back to each subject's original brain coordinates. For the control group the most significant activation in the low frequency band was in the contralateral motor region. In the high frequency band, significant activations were found in bilateral motor regions. In the DS group, we observed two distinct patterns of activation: an ipsilateral dominance and a contralateral dominance in the low frequency band. DS individuals were subsequently divided into two subgroups based on laterality calculated in the broadband (0.2-SOHz). The ipsilateral group (n=6) showed largest activations in the right temporal region at low frequencies. At high frequencies the distribution was bilateral, involving both motor and temporal regions. The strongest peaks in the contralateral group (n=6) were found in the left motor area for both low and high frequency bands. PLV analysis showed significant differences in connected locations between the controls and the DS ipsilateral and contralateral groups. Further work is needed to better understand the emergence of these two distinct patterns of neural activity.